1. Field of the Invention
The present invention relates to an apparatus and method for detecting a motion vector, a program, and a recording medium, and in particular, to a motion vector detecting apparatus and method capable of detecting a motion vector which is not detected even when the number of candidate vectors is increased, a program therefor, and a recording medium with the program recorded.
2. Description of the Related Art
In motion compensation image coding for high efficiency coding of moving image signals, traffic monitoring systems, and visual sensors, processing of detecting a moving object needs a process of detecting the direction of motion of an object included in an image and the size of the object, i.e., detecting a motion vector. A method of efficiently and accurately detecting a motion vector in units of pixels is disclosed in Japanese Unexamined Patent Application Publication No. 2005-175870 assigned to the same assignee as this application.
According to this method, the previous frame image signal is divided into a plurality of blocks each including m×n pixels and a pixel located in, for example, the center of each block is set to a representative point. A search area is set in the current frame. The difference between each representative point and each of pixels in the search area is calculated as an evaluation value. The evaluation values corresponding to the number of pixels in the search area are obtained.
When each pixel is expressed by eight bits, each evaluation value is also expressed by eight bits. Each evaluation value is compared to a variable threshold, so that the evaluation value is degenerated into one bit. The evaluation values in one frame are accumulated such that each evaluation value is related to the corresponding pixel position in the search area, so that an evaluation value table having a size corresponding to the search area is generated. A motion vector is detected on the basis of a peak evaluation value in the evaluation value table.